Semiconductor device

ABSTRACT

A semiconductor device includes a semiconductor substrate having a first surface, a through silicon via (TSV) that is formed so that at least a part thereof penetrates through the semiconductor substrate, and an insulation ring. The insulation ring is formed so as to penetrate through the semiconductor substrate and so as to surround the TSV. The insulation ring includes a tapered portion and a vertical portion. The tapered portion has a sectional area which is gradually decreased from the first surface toward a thickness direction of the semiconductor substrate. The vertical portion has a constant sectional area smaller than the tapered portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/226,541filed on Sep. 7, 2011, which claims the benefit of priority fromJapanese Patent Application No. 2010-206858, filed on Sep. 15, 2010, thedisclosures of which are incorporated herein in its entirety byreference.

TECHNICAL FIELD

The invention relates to a semiconductor device.

BACKGROUND ART

When manufacturing a semiconductor device, a process of forming anopening (via hole) has been used in many cases. As disclosed in JP2007-311584A and JP 2009-044031A, a Bosch process has been known as ameans for forming a deep opening having a vertical shape in asemiconductor substrate such as silicon. The Bosch process is atechnology that repeats an etching process of isotropically etching asurface of the semiconductor substrate to form an opening and adeposition process of depositing a carbon polymer-based protective filmon an inner wall of the opening alternately, thereby etching thesemiconductor substrate vertically and deeply.

FIG. 21 is a sectional view of an opening 31 that is formed in asemiconductor substrate 30 by the Bosch process according to the relatedart. In the Bosch process, since the etching process and the depositionprocess are repeated, it is known that a sectional shape of a waveformreferred to as scalloping (which is indicated with ‘S’) is formed onside surface of the opening.

FIG. 22 shows an opening forming method using the Bosch processaccording to the related art. A mask 32 having an opening pattern isformed on the semiconductor substrate 30 with a photoresist film and thelike.

As shown in FIG. 22A, in a first cycle, a first opening 31-1 is formedby dry etching having high isotropy and using etching gas (first etchingprocess).

As shown in FIG. 22B, a protective film 33 that covers an inner wall ofthe first opening 31-1 and a top surface of the mask 32 is deposited byusing deposition gas (deposition process).

As shown in FIG. 22C, the dry etching in which the anisotropy isincreased by using the etching gas is performed to remove the protectivefilm on a bottom of the first opening 31-1 (second etching process). Theprotective film 33 a remains on side surface of the first opening 31-1.

As shown in FIG. 22D, in a second cycle, a second opening 31-2 is formedby the isotropic dry etching (first etching process). When performingthe etching, a part of the protective film 33 a is also removed.

By repeating the series of cycles more than once (for example, 200times), the opening 31 having the substantially vertical shape and apredetermined depth as shown in FIG. 21 is formed.

SUMMARY OF THE INVENTION

In one embodiment, there is provided a semiconductor device, comprising:

a semiconductor substrate including a first surface;

a through silicon via, at least part of the through silicon viapenetrating through the semiconductor substrate; and

an insulation ring penetrating through the semiconductor substrate andsurrounding the through silicon via, the insulation ring comprising atapered portion with a sectional area decreased gradually from the firstsurface toward a thickness direction of the semiconductor substrate anda vertical portion with a constant sectional area smaller than thesectional area of the tapered portion.

In another embodiment, there is provided a semiconductor device,comprising:

a semiconductor substrate including a first surface;

a through silicon via, at least part of the through silicon viapenetrating through the semiconductor substrate; and

an insulation ring penetrating through the semiconductor substrate andsurrounding the through silicon via, the insulation ring comprising atapered portion and a vertical portion,

wherein the tapered portion and the vertical portion include an innerside surface and an outer side surface surrounding the through siliconvia,

in the tapered portion, a length between the inner side surface andouter side surface is gradually decreased from the first surface towarda thickness direction of the semiconductor substrate, and

in the vertical portion, a length between the inner side surface andouter side surface is constant smaller than the length between the innerside surface and outer side surface in the tapered portion.

In another embodiment, there is provided a semiconductor device,comprising:

a semiconductor substrate having a first surface and a second surfaceopposite to the first surface;

an insulating ring formed in the semiconductor substrate to penetratethrough the semiconductor substrate from the first surface to the secondsurface;

a first interlayer insulating film formed over the first surface of thesemiconductor substrate to cover the insulating ring;

a transistor formed on the first surface of the semiconductor substrate;

an insulating layer formed on the second surface of the semiconductorsubstrate to cover the insulating ring;

a through silicon via (TSV) formed in the semiconductor substrate topenetrate through the insulating layer, the semiconductor substrate, andthe first interlayer insulating film inside of the insulating ring;

a first wiring formed on the first interlayer insulating film to connectto the TSV;

a second interlayer insulating film formed over the first interlayerinsulating film to cover the first wiring;

a contact plug formed in the second interlayer insulating film topenetrate through the second interlayer insulating film;

a first bump formed on the TSV; and

a second bump formed on the second interlayer insulating film to connectto the contact plug,

wherein the insulating ring includes a tapered portion in contact withthe first surface of the semiconductor substrate, and a vertical portionin contact with the second surface of the semiconductor substrate,

wherein each of the tapered portion and the vertical portion includes asurface to define a boundary with the semiconductor substrate,

wherein the surface of the tapered portion comprises a first convex arcand a second convex arc connected in series, the first convex arc isplaced closer to the first surface of the semiconductor substratecompared with the second convex arc, and the first convex arc is largerthan the second convex arc, and

wherein the surface of the vertical portion comprises a plurality ofthird convex arcs connected in series, the third convex arcs are smallerthan the first convex arc and the second convex arc, and each of thethird convex arcs is substantially identical to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present invention will be moreapparent from the following description of certain preferred embodimentstaken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a semiconductor device of a first exemplary embodiment.

FIGS. 2 to 17 show a method of manufacturing the semiconductor device ofthe first exemplary embodiment.

FIGS. 18 and 19 show a semiconductor device of a second exemplaryembodiment.

FIG. 20 shows a semiconductor device of a third exemplary embodiment.

FIGS. 21 and 22A, 22B, 22C, and 22D show a method of manufacturing asemiconductor device of the related art.

FIGS. 23A and 23B show a first modified embodiment of the firstexemplary embodiment.

FIGS. 24A and 24B show a second modified embodiment of the firstexemplary embodiment.

FIGS. 25A and 25B illustrate the semiconductor device of the firstexemplary embodiment.

In the drawings, reference numerals have the following meanings: 1:semiconductor substrate, 2: mask pattern, 3-1, 3-2, 3-3, 3-10: opening,4, 4 a: protective film, 5: first surface, 6: second surface, 10:insulation film, 11: thickness direction, 22, 31, 31-1, 31-2: opening,30: semiconductor substrate, 32: mask pattern, 33, 33 a: protectivefilm, 35: insulation film, 36: void, 50: semiconductor substrate, 51:gate insulation film, 57: isolation region, 83: liner, 85, 86, 98, 105,107, 110: interlayer insulation film, 93: metal film, 100: semiconductorchip, 106, 109, 112: wiring, 111: silicon nitride film, 113: protectivefilm, 114: N-type well, 120: P-type impurity diffusion layer, 121:N-type impurity diffusion layer, 124, 126: peripheral contact hole, 125:silicide layer, 127: local wiring, 130, 131, 132: contact plug, 140:topside bump, 141: seed film, 142: copper bump, 143: surface metal film,150: insulation ring, 150 a: inner side surface, 150 b: outer sidesurface, 150 c: trench for insulation ring, 151: opening (hole), 155:silicon nitride film, 160: backside bump, 161: seed film, 162: copperbump, 163: backside metal film, 200: TSV (Through Silicon Via), 321:base substrate, 322, 323, 324: semiconductor chip, 323 a: backside bump,323 b: topside bump, 323 c: TSV, 325: attaching film, 326: lead frame,327: soldered ball, 328: wiring layer, 329: terminal, 330: resin, 400:printed substrate, 401: I/O terminal, 402: DRAM package, 403: controlchip, 500: data processing device, 502: calculation processing device,510: system bus, 520: calculation processing device, 530: DRAM memorymodule, 540: ROM (Read Only Memory), 550: non-volatile storage device,560: I/O device, D: device region, S: scalloping, T1: tapered portion,T2: vertical portion, TV: TSV region, V: through-plug

DESCRIPTION OF PREFERRED ILLUSTRATIVE EMBODIMENTS

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposes.

First Exemplary Embodiment

A specific semiconductor device according to this present exemplaryembodiment will be explained with reference to FIGS. 1 to 10. FIG. 1 isa sectional view of a semiconductor chip including a through silicon via(TSV), which is a semiconductor device of this exemplary embodiment. Thesemiconductor chip may include a storage device such as DRAM, SRAM,flash memory and the like and a calculation processing device such asMPU, DSP and the like.

As shown in FIG. 1, a semiconductor chip 100 comprises a device region Dand a TSV region TV. In the device region D, a device such as MOStransistor is arranged, so that a predetermined circuit is configured.In the TSV region, a plurality of TSVs 200 are arranged. In FIG. 1, onlyone TSV is shown.

The TSV 200 includes bumps (protrusion electrodes) for connection atupper and lower ends. When stacking a plurality of semiconductor chips,the semiconductor chips, which are arranged above and below, areelectrically connected to each other via the TSV 200. The TSV 200includes a through-plug V penetrating the semiconductor substrate 50, acontact plug penetrating a plurality of interlayer insulation films onthe semiconductor substrate 50 and a wiring layer. An insulation ring150 is provided around a part of the TSV embedded in the semiconductorsubstrate. By the insulation ring, the insulation among the individualTSV 200, the other TSVs and the device region D is secured.

The insulation ring 150 is formed by filling a ring-shaped openingformed in the semiconductor substrate 50 with a silicon oxide film byusing the manufacturing method of this exemplary embodiment. An endportion of the TSV on a backside (a lower side of FIG. 1) of thesemiconductor substrate 50 constitutes a backside bump 160. In otherwords, a part of the backside bump 160 penetrates through thesemiconductor substrate.

FIG. 25A is an enlarged view of a part of the semiconductor devicesurrounded by the dotted line of FIG. 1 and FIG. 25B is a sectional viewtaken along a line A-A of FIG. 25A. In FIG. 25, the scalloping isomitted. As shown in FIG. 25, the insulation ring 150 is provided tosurround a part of the backside bump 160. The insulation ring 150 has atapered portion X and a vertical portion Y. The tapered portion X has asectional area that is gradually decreased from a first surface 5 towarda thickness direction of the semiconductor substrate 50. The verticalportion Y has a constant sectional area that is smaller than the minimumvalue of the sectional area of the tapered portion and the sectionalarea thereof is not changed in the thickness direction of thesemiconductor substrate 50. In addition, the insulation ring 150 has twoside surfaces, i.e., an inner side surface 150 a and an outer surface150 b surrounding the backside bump. In the tapered portion, a distanceL₁ between the two side surfaces is gradually decreased from the firstsurface 5 toward the thickness direction of the semiconductor substrate50. In the vertical portion, a distance L₂ between the two side surfacesis constant and is not changed in the thickness direction of thesemiconductor substrate 50. In addition, the distance L₂ is smaller thanthe minimum value of the distance L₁ between the two side surfaces ofthe tapered portion.

As shown in FIG. 1, an end portion of the TSV on a topside (an upperside of FIG. 1) of the semiconductor substrate 50 constitutes a topsidebump 140. When stacking the plurality of semiconductor chips, thebackside bump 160 is bonded with the topside bump 140 provided to thelower chip. The through plug V having integrated with the backside bump160 penetrates through the semiconductor substrate 50 and is connectedto a local wiring (local wiring layer) 127. The local wiring 127 is alsoprovided to the device region D and is used as a part of the wiringlayer configuring the circuit.

The local wiring 127 connected to the through plug V is connected to afirst wiring 106 of the upper layer via first contact plugs 130. Thefirst wiring 106 is connected to a second wiring 109 of the upper layervia second contact plugs 131. The second wiring 109 is connected to athird wiring 112 of the upper layer via third contact plugs 132. Thetopside bump 140 is formed so as to connect to the third wiring 112. Inthe meantime, although not shown, the topside bump 140 and the backsidebump 160 of the TSV 200 may be connected with each other and the TSV mayinclude an internal wiring that is electrically connected to the MOStransistor formed in the device formation region D through any one ofthe local wiring 127, the first wiring 106, the second wiring 109 andthe third wiring 112. In addition, as required, one of the first tothird contact plugs may be omitted to form an electrode in which thetopside bump 140 and the backside bump 160 are not electricallyconnected therebetween.

In the below, a method of manufacturing the semiconductor deviceincluding the TSV will be explained.

As shown in FIG. 2, a semiconductor substrate 50 of P-type silicon (Si)is prepared and a trench for insulation ring 150 c for an insulationring is formed in the TSV region TV. The trench for insulation ring 150c has a ring shape, when from a plan view, so as to surround the throughplug V that will be formed later. In FIG. 2, the scalloping on the sidesurface of the opening is omitted for simplification (which is also thesame as in FIGS. 10-18).

In the below, a method of forming the trench for insulation ring 150 cwill be specifically explained with reference to FIGS. 3 to 9. In FIGS.3 to 9, a shape of the scalloping is exaggerated for clear explanation.

As shown in FIG. 3, a mask pattern 2 including an opening is formed onthe semiconductor substrate 50 using silicon. A material of the maskpattern 2 is not particularly limited as long as it has resistance tothe etching. For example, the mask pattern 2 can be formed by using aphotoresist film, a silicon oxide film (SiO₂), a silicon nitride film(Si₃N₄) and the like. An opening is formed in a region of thesemiconductor substrate 50, which is not covered by the mask pattern 2.In this exemplary embodiment, it is not necessary to beforehand form aspecial step shape in the mask pattern 2.

As the etching apparatus, it is possible to use a single wafer highdensity plasma etching apparatus of an ICP (inductively-coupled plasma)manner. As a first etching process in a first cycle, the dry etchinghaving high isotropy is performed using SF₆ gas, thereby forming a thirdopening 3-1 having a depth d1. The specific etching conditions may beexemplified as follows.

gas type: SF₆

gas flow rate: 230 to 270 sccm

pressure: 80 to 100 mTorr

source power: 2300 to 2700 W.

In this exemplary embodiment, in the first cycle, the etching time offour seconds is set, so that the third opening 3-1 having the depth d1of about 1 μm is formed. In the etching process, bias power iscontrolled separately from source power for controlling a density of theplasma, so that the energy of ions reaching the semiconductor substrateis controlled to optimally set a degree of the isotropy.

In the first etching process, the bias power that is applied to thesemiconductor substrate is set so as to be weak (for example, 50 to 60W) and the side etching is made. Thereby, the etching can be performedwith the high isotropy.

As shown in FIG. 3, as a deposition process in the first cycle, the sameetching device is used to form a protective film 4 that covers an innerwall of the third opening 3-1. The specific deposition conditions may beexemplified as follows.

gas type: C₄F₈

gas flow rate: 230 to 270 sccm

pressure: 60 to 80 mTorr

source power: 2300 to 2700 W.

In the deposition process, the bias power is not applied. By thedeposition process, the protective film 4, which includes, as a maincomponent, fluoro carbon-based polymer, is formed so as to cover theinner wall of the third opening 3-1 and a top surface of the maskpattern 2.

As shown in FIG. 4, as a second etching process in the first cycle, thesame etching device is used to perform the dry etching having highanisotropy and using the same gas as the first etching process, so thatthe protective film 4 deposited on a bottom surface of the third opening3-1 is removed. The specific etching conditions may be exemplified asfollows.

gas type: SF₆

gas flow rate: 230 to 270 sccm

pressure: 60 to 80 mTorr

source power: 2300 to 2700 W.

In the second etching process, the bias power that is applied to thesemiconductor substrate is set to be stronger (for example, 150 to 160W) than that of the first etching process and the side etching is thussuppressed. Thereby, it is possible to perform the etching with the highanisotropy. Thus, it is possible to remove the protective film on thebottom surface of the third opening 3-1 while remaining the protectivefilm 4 a on the inner wall side surface of the third opening 3-1.

By sequentially performing the first etching process, the depositionprocess and the second etching process, as described above, the firstcycle of the etching process is completed.

As shown in FIG. 5, at the state in which the inner wall side surface ofthe third opening 3-1 are covered by the protective film 4 a (in FIG. 5,the protective film 4 a is not shown. The protective film 4 a is notshown in the below drawings), a second cycle including the first etchingprocess, the deposition process and the second etching process isperformed, like the first cycle. At this time, the gas type, thepressure, the applying power used and the like are set to be the same asthose in the respective processes of the first cycle. However, the firstetching process is performed on condition that the etching time of thefirst etching process is shortened by predetermined time t1. In thisexemplary embodiment, t1 is one second and the etching is performed forthree seconds. Thereby, a third opening 3-2 having a depth d2 of about0.75 μm is formed.

Since the inner wall side surface of the third opening 3-1 are coveredwith the protective film 4 a, the side etching does not proceed. In themeantime, a part of the protective film 4 a is also removed by theetching. In this exemplary embodiment, the second cycle is set so thatthe etching time of the first etching process is shorter by t1 than thefirst cycle. Thereby, the depth d2 of the third opening 3-2 becomesshallower than the depth d1 of the third opening 3-1 and the sideetching amount of the third opening 3-2 becomes also smaller than thatof the third opening 3-1. On the other words, the depth d1 maycorrespond to a first convex arc, and the depth d2 may correspond to asecond convex arc. The first convex arc is larger than the second convexarc. The first convex arc may be placed to be indented from a center ofthe third opening 3-1, (a center of an insulating ring 150 shown in FIG.10), compared with the second convex arc. The word “convex” can betranslated to “concave” from point of view of the semiconductorsubstrate 1.

Continuously, like the first cycle, the deposition process and thesecond etching process are sequentially performed, so that the secondcycle is completed. At the completion time of the second cycle, theinner wall side surface of the third openings 3-1, 3-2 are covered withthe protective film 4 a.

As shown in FIG. 7, at the state in which the inner walls of the thirdopenings 3-1, 3-2 are covered with the protective film 4 a, a thirdcycle including the first etching process, the deposition process andthe second etching process is performed, like the second cycle. At thistime, the gas type, the pressure, the applying power used and the likeare set to be the same as those in the respective processes of the firstcycle. However, the first etching process is performed on condition thatthe etching time of the first etching process is shortened bypredetermined time t1, compared to the second cycle. In this exemplaryembodiment, t1 is one second and the etching is performed for twoseconds. Thereby, a third opening 3-3 having a depth d3 of about 0.5 μmis formed.

Since the inner wall side surface of the third openings 3-1, 3-2 arecovered with the protective film, the side etching does not proceed. Inthis exemplary embodiment, the third cycle is set so that the etchingtime of the first etching process is shorter by t1 than the secondcycle. Thereby, the depth d3 of the third opening 3-3 becomes shallowerthan the depth d2 of the third opening 3-2 and the side etching amountof the third opening 3-3 becomes also smaller than that of the thirdopening 3-2.

Continuously, like the second cycle, the deposition process and thesecond etching process are sequentially performed, so that the thirdcycle is completed.

By performing the first to third cycles, a first opening having atapered shape is formed. In the specification, each opening, which isformed every one cycle in the first to third cycles, is referred to as‘third opening’, and an opening having a tapered shape and including theplurality of third openings is referred to as ‘first opening.’

As shown in FIG. 8, in the cycles after the fourth cycle, the etchingtime of the first etching process is fixed with time shorter than theetching time in the first etching process of the third cycle. In thisexemplary embodiment, the etching time of the first etching process isfixed with one second. By repeating the cycle several time, in which thefirst etching time having the fixed etching time, the deposition processand the second etching process are sequentially performed, a secondopening having a predetermined depth is formed. In FIG. 8, it is shownthat fourth openings 3-10 are formed by performing the cycle up to tenthcycle. In the specification, each opening, which is formed every onecycle in the fourth to tenth cycles, is referred to as ‘fourth opening’,and an opening having substantially vertical inner wall side surface andincluding the plurality of fourth openings is referred to as ‘secondopening.’

From the fourth cycle to the tenth cycle, the depths d4 to d10 of thefourth openings that are formed in the respective cycles are thesubstantially same. In addition, the side etching amount of each fourthopening is also the substantially same. Thereby, in the fourth to tenthcycles, it is possible to form a second opening having a substantiallyvertical shape. In other words, the depths d4 to d10 may correspond to aplurality of third convex arcs connected in series. The third convex arcis smaller than the first convex arc and the second convex arc. Each ofthe third convex arcs is substantially identical to each other.

FIG. 8 shows the first to tenth cycles. However, by repeating the samecycle, it is possible to deepen a depth of the second opening. After thefourth cycle, the etching time of the first etching process in which theside etching is performed is set to be shorter than the third cycle.Accordingly, a concavo-concave shape of the scalloping formed on theside surface of the fourth opening becomes sufficiently small.

After the first etching process is completed in the final cycle, anashing process may be performed by using the oxygen gas so as to removethe protective film remaining in the opening.

A sectional view of the opening finally formed is shown in FIG. 9. Inthis exemplary embodiment, it is possible to form an opening (hole)including a first opening T1 having a tapered shape at an upper end anda second opening T2 having a substantially vertical shape by using theBosch process.

In the second opening T2, an opening having the substantially equivalentarea to an opening area of the mask pattern 2 is formed. In the firstopening T1, an opening having an area larger than an opening area of themask pattern 2 at the uppermost end is formed.

Since each of the third openings formed in the first opening T1 has theshape formed by the isotropic etching, the inner wall side surface ofeach third opening have a recessed shape. Accordingly, each of the thirdopenings has a sectional area S_((n)) (n: an integer of 1 or greater) ofa section perpendicular to a thickness direction of the semiconductorsubstrate 50, which is changed as each of the third openings proceedtoward an inward direction 11 (a direction proceeding from the firstsurface 5 of the semiconductor substrate 50 to a second surface 6 thatis a backside) of the semiconductor substrate in the thicknessdirection. Also, in one third opening, the sectional area S_((n)) isgradually increased as the third opening proceeds from a positionclosest to the first surface 5 along the direction 11, so that it hasthe maximum value S_((n)max) at a substantially half depth of thethickness direction of the silicon substrate 50. The sectional areaS_((n)) is gradually decreased as the third opening further proceedsfrom the substantially half depth of the thickness direction along thedirection 11. In other words, in one third opening, the sectional areaS_((n)) is the smallest at the position closest to the first surface 5between the position closest to the first surface 5 and the position ofthe substantially half depth of the thickness direction of the siliconsubstrate 50. Likewise, in one third opening, the sectional area S_((n))is the smallest at a position farthest from the first surface 5 betweenthe position of the substantially half depth of the thickness directionof the silicon substrate 50 and the position farthest from the firstsurface 5.

Here, the sectional area of the n^(th) third opening from the firstsurface 5 toward the thickness direction 11 is indicated with S_((n)).For example, for the 1^(st) third opening, the sectional area S₍₁₎ hasS_((1)max) at a position of the depth L₁. Likewise, for the 2^(nd) thirdopening from the first surface 5 toward the thickness direction, thesectional area S₍₂₎ has S_((2)max) at a position of the depth L₂.

By stepwise shortening the time of the first etching process of thefirst cycle in which the first opening T1 is formed, the side etching isstepwise decreased, resulting in obtaining a tapered shape, in which themaximum value S_((n)max) of the sectional area of each third opening isdecreased as the first opening proceeds toward the thickness direction11.

The tapered shape is not configured by a smooth tapered surface. Asdescribed above, since the side surface of each third opening have arecessed shape by the isotropic etching, the tapered shape is configuredby a surface having a concavo-concave shape. In addition, the depth ofeach third opening is gradually decreased as the third opening proceedsin the inward direction 11 of the thickness direction of thesemiconductor substrate 50.

Since each of the fourth openings formed in the second opening T2 hasthe shape formed by the isotropic etching, the inner wall side surfaceof each fourth opening have a recessed shape. Accordingly, each of thefourth openings has a sectional area S′_((a)) (a: an integer of 1 orgreater) of a section perpendicular to the thickness direction of thesemiconductor substrate 50, which is changed as the fourth openingproceeds toward the inward direction 11 of the semiconductor substratewith respect to the thickness direction. Also, in one fourth opening,the sectional area S′_((a)) is gradually increased as the fourth openingproceeds from a position closest to the first surface 5 along thedirection 11, so that it has the maximum value S′_((a)max) at asubstantially half depth of the thickness direction of the siliconsubstrate 50. The sectional area S′_((a)) is gradually decreased as thefourth opening further proceeds from the substantially half depth of thethickness direction along the direction 11. In other words, in onefourth opening, the sectional area S′_((a)) is the smallest at theposition closest to the first surface 5 between the position closest tothe first surface 5 and the position of the substantially half depth ofthe thickness direction of the silicon substrate 50. Likewise, in onefourth opening, the sectional area S′_((a)) is the smallest at aposition farthest from the first surface 5 between the position of thesubstantially half depth of the thickness direction of the siliconsubstrate 50 and the position farthest from the first surface 5.

Here, the sectional area of the fourth opening closest to the firstsurface 5 regarding the thickness direction of the silicon substrate 50is indicated with S′₍₁₎ and the sectional area of the a^(th) fourthopening as the second opening proceeds in the thickness direction 11 isindicated with S′_((a)). For example, for the 1^(st) fourth opening, thesectional area S′₍₁₎ has S′_((1)d max) at a position of the depth M₁from the first surfaces of the silicon substrate 50. Since therespective fourth openings are formed under the same conditions, themaximum values S′_((a)max) of the sectional areas of the respectivefourth openings are the same. In addition, the depths of the respectivefourth openings are also the same. By performing the formation of thefourth opening under the same conditions at least two times, the secondopening T2 is formed.

In the above description, the first opening is formed in the three-stepcycles. However, the first opening may be formed by increasing thenumber of cycles more than the above described process. In addition, thetime that is used in the first etching process may be also arbitrarilyset. In other words, in this exemplary embodiment, the etching time(time E1) of the first etching process in the first cycle is first setdepending on an opening width (side etching width) to be formed. Inaddition, the step time t1 of decreasing the etching time is set.

Next, the etching time En of the first etching process in the n^(th)cycle (n: integer of 2 or greater) is set so that En=E1−t1×(n−1), andthe process is sequentially performed up to the n^(th) cycle.Continuously, the cycle is performed k times (k: integer of 2 orgreater), so that the first etching process is performed for the time E1that is fixed to be longer than the etching time En of the first etchingprocess in the n^(th) cycle that has been finally performed in theprocess of forming the first opening, thereby the second opening isformed.

In this exemplary embodiment, the opening width of the upper end of thefirst opening can be enlarged by performing the first cycle only onetime when forming the first opening. However, it is preferable toperform the cycle of forming the first opening at least two times (n=2or greater) so as to improve the embedding characteristic of theinsulation film and the like into the opening. This is because when thecycle of forming the first opening is performed only one cycle, theopening width is rapidly changed at a boundary between the first openingand the second opening, so that an insulation film to be embedded may beeasily blocked at the boundary. Since the smooth tapered shape isobtained by setting the step time t1 small and increasing the number ofcycles n for forming the tapered shape, the improvement effect on theembedding characteristic of the insulation film is increased.

The above manufacturing conditions (gas flow rate, pressure and thelike) described in the first and second etching processes and depositionprocess are simply exemplary and can be changed as long as it does notdepart from the scope of the invention. It is easiest to control theshape of the first opening by changing the etching time of therespective cycles, as described above. However, the shape of the firstopening can be controlled by gradually changing the applying conditionof the bias power in the first etching process of performing the etchinghaving high isotropy every cycle (for example, by increasing the biaspower every one cycle).

The above formation conditions of the first and second openings areexemplary and may be appropriately changed depending on the depths andopening widths of the first and second openings. For example, it ispossible to form the trench for insulation ring 150 c having a depth ofabout 45 μm, the tapered portion having a depth of about 3 to 4 μm andthe vertical portion having an opening width of about 2 to 3 μm. In thiscase, contrary to the above conditions, by setting the initial value ofthe etching time E1=4 seconds and the step time t1=0.5 second andrepeating the five-step cycles (k=5), it is possible to form the firstopening. In addition, the second opening is formed by repeating thecycle about 200 times.

As shown in FIG. 10, a silicon nitride film 111 is formed to cover theinner wall of the trench for insulation ring 150 c by a CVD method andthen the insulation film 150 c is filled with a silicon oxide film 112using the CVD method. The silicon nitride film 111 and the silicon oxidefilm 112 on the top surface of the semiconductor substrate are removedby the etching so that the silicon nitride film 111 and the siliconoxide film 112 remain only in the trench for insulation ring 150 c.Thereby, the insulation ring 150 is formed.

In this exemplary embodiment, the formed trench for insulation ring 150c has an aspect ratio of about 15 to 20. Accordingly, when a recesshaving a vertical shape is formed by the related art, it is difficult tofill the recess with the silicon oxide film 112 so that a void is notformed in the recess. To the contrary, according to this exemplaryembodiment, the trench for insulation ring 150 c is formed to includethe tapered portion, to prevent a void from being formed in the trenchfor insulation ring when filling the recess with the silicon oxide film112. Thereby, it is possible to prevent a crack from being generatedfrom the insulation ring 150 during the manufacturing process, therebysuppressing the manufacturing yield from being lowered.

As shown in FIG. 11, in the device region D, isolation regions 57 fordividing activation areas of MOS transistors are formed by an STImethod. The N-type impurities such as phosphorous are introduced intothe semiconductor substrate 50 by ion implantation, to form an N-typewell 114 is formed. In the N-type well 114, a P channel-type MOStransistor is disposed in a later process. Likewise, boron (B) may beion-implanted in a region except for the N-type well, thereby forming aP-type well.

After the surface of the clean semiconductor substrate 50 is exposed, agate insulation film 51 is formed on the surface of the semiconductorsubstrate 50 by a silicon oxide film formed by a thermal oxidationmethod and the like and having a film thickness of about 4 to 7 nm. Asthe gate insulation film 51, a high-K film (high dielectric film) may beused.

As shown in FIG. 12, a gate electrode GP and a P-type impurity diffusionlayer 120 of the P channel-type MOS transistor and a gate electrode GNand an N-type impurity diffusion layer 121 of the N channel-type MOStransistor are formed. The P-type impurity diffusion layer 120 functionsas source/drain electrodes of the P channel-type MOS transistor. TheN-type impurity diffusion layer 121 functions as source/drain electrodesof the N channel-type MOS transistor. The source/drain electrodes may beformed so as to include an LDD structure by forming side wall insulationfilms on the side surfaces of the gate electrodes GP, GN.

Continuously, a liner film 83 is formed on the semiconductor substrate50 with a silicon nitride film having a film thickness of about 10 to 20nm. Next, after an SOD (Silicon On Directrics; applied insulation filmsuch as poly-silazane) film is deposited by a spinner method, anannealing process is performed under high-temperature vapor (H₂O)atmosphere, thereby modifying the solid deposited film and thus forminga first interlayer insulation film 85. The liner film 83 is formed bythe oxidation-resistant film to prevent a device of the lower layer,which has been already formed, from being oxidized and damaged whenannealing the SOD film.

Continuously, after a top surface of the first interlayer insulationfilm 85 is smoothed by a CMP process, a silicon oxide film is formed asa second interlayer insulation film 86 by the CVD method, therebycovering the surface of the first interlayer insulation film 85. Insteadof the stacked structure of the first interlayer insulation film 85 andthe second interlayer insulation film 86, it may be possible to deposita silicon oxide film at one time by the CVD method.

Next, peripheral contact holes 124 reaching the P-type impuritydiffusion layer 120 and the N-type impurity diffusion layer 121 in thedevice region D are formed by anisotropic dry etching in which aphotoresist film is used as a mask pattern. A silicon surface of thesemiconductor substrate 50 is exposed on bottoms of the peripheralcontact holes 124.

Continuously, a silicide layer 125 such as cobalt silicide (CoSi) isformed on the silicon-exposed parts of the semiconductor substrate 50.After that, a metal film such as tungsten is deposited so as to fill theperipheral contact holes 124. The CMP process is performed so that themetal film 93 such as tungsten remains only in the peripheral contactholes 124. Thereby, peripheral contact plugs 126 that are conducted tothe source/drain electrodes of the transistors are formed in the deviceregion D.

As shown in FIG. 13, tungsten nitride (WN) and tungsten (W) aresequentially deposited to form deposited films, which are then patternedto form local wirings 127. In the device region D, the local wirings 127are connected to the peripheral contact plugs 126. The local wiring 127is also disposed in the TSV region TV.

The local wiring 127 that is disposed in the TSV region TV may beconducted with the other local wiring 127 at a part (not shown). Thelocal wiring 127 that is disposed in the TSV region TV functions as apad for connection to a TSV plug V that is to be formed in a subsequentprocess. Next, a liner film 97 is formed to cover the local wirings 127by using a silicon nitride film and then a third interlayer insulationfilm 98 is used using an SOD film.

As shown in FIG. 14, a silicon oxide film is formed as a fourthinterlayer insulation film 105 by the CVD method, thereby covering asurface of the third interlayer insulation film 98. Instead of thestacked structure of the third interlayer insulation film 98 and thefourth interlayer insulation film 105, a silicon oxide film may bedeposited at one time by the CVD method. After that, local contact plugs130 that are connected to the local wirings 127 in the device region Dare formed using a metal film such as tungsten. The local contact plugs130 are also formed to connect to the local wiring 127 that is disposedin the TSV region TV.

Next, first wirings 106 of the upper layer are formed using aluminum(Al), copper (Cu) and the like. In the device region D and the TSVregion TV, the first wirings 106 are formed to connect to the localcontact plugs 130. A fifth interlayer insulation film 107 is formed tocover the first wirings 106 using a silicon oxide film and the like.First contact plugs 131 that are connected to the first wirings 106 areformed by a metal film such as tungsten and the like.

Next, second wirings 109 are formed using aluminum (Al), copper (Cu) andthe like. In the device region D and the TSV region TV, the secondwirings 109 are formed to connect to the first contact plugs 131. Asixth interlayer insulation film 110 is formed to cover the secondwirings 109 using a silicon oxide film and the like. Second contactplugs 132 that are connected to the second wirings 109 are formed usinga metal film such as tungsten and the like in the TSV region TV.

Next, a third wiring 112 is formed using aluminum and the like. Thethird wiring 112 is a wiring layer of the uppermost layer and alsoserves as a pad when forming a bump electrode on a surface thereof.Accordingly, it is preferable not to use a metal film that is apt to benaturally oxidized, such as copper (Cu) and the like. Also in the deviceregion D, the third wiring may be disposed and used as a wiring layerthat is connected to the second wirings 109. A surface protective film113 is formed using a silicon oxynitride (SiON) and the like so as tocover the third wiring 112. In the meantime, when forming the secondwirings 109 or third wiring 112, a dual damascene method or aluminumreflow method may be used to form the contact plugs that are connectedto lower surfaces of the respective wirings and to form the wiring layerat the same time.

Continuously, a process for forming a through silicon via in the TSVregion TV will be described.

As shown in FIG. 15, the third wiring 112 of the uppermost layer that isdisposed in the TSV region TV functions as a pad for forming a topsidebump. An opening (hole) is formed in the protective film 113 so as toexpose the upper surface of the third wiring 112 and a topside bump 140that is connected to the third wiring is formed. The topside bump 140 isformed by three layers of a seed film 141 including copper deposited ona titanium (Ti) film, a copper bump 142 and a surface metal film 143. Asthe surface metal film 143, an alloy film (Sn—Ag film) of tin and silverhaving a film thickness of about 2 to 4 μm may be exemplified. Thecopper bump 142 is formed so as to have a height (bump film thickness)of about 10 to 12 μm by an electrolytic plating method.

As shown in FIG. 16, a support substrate (not shown) of acrylic resin,quartz and the like is bonded on the surface side (upper surface side inFIG. 16) of the semiconductor substrate 50 via an adhesive layer and thebackside (lower surface side in FIG. 16) of the semiconductor substrate50 is then ground (back grinding) to reduce a film thickness up to apredetermined thickness (for example, 40 μm). By the grinding process, abottom of the insulation ring 150 that has already been formed isexposed on the backside of the semiconductor substrate 50. A siliconnitride film 155 is formed to have a film thickness of about 200 to 400nm so as to cover the backside of the semiconductor substrate 50. Thesilicon nitride film 155 prevents the copper, which is used for the TSVplugs V to be formed in a subsequent process, from diffusing into thesemiconductor substrate from the backside thereof during themanufacturing process and thus influencing the device characteristicsadversely.

As shown in FIG. 17, an opening (hole) 151 is formed by the anisotropicdry etching so that a backside of the local wiring 127, which isdisposed in the TSV region TV, is exposed. The opening 151 is formed topenetrate through the silicon nitride film 155, the semiconductorsubstrate 50, the liner film 83, the first interlayer insulation film 85and the second interlayer insulation film 86. At a bottom side (theupper side in FIG. 17) of the opening 151, the backside of the localwiring 127 is exposed. The dry etching of forming the opening 151 may beperformed in two steps of the silicon etching of the semiconductorsubstrate 50 and the insulation film etching of the first interlayerinsulation film 85 and the like separately. In addition, regarding thesilicon etching of the semiconductor substrate 50, the conventionalBosch process having no tapered portion may be used because a size ofthe opening is sufficiently large.

Next, as shown in FIG. 1, the backside bump 160 integrated with thethrough-plug V filling the inside of the opening 151 is formed. Thebackside bump 160 is made of three layers of a seed film 161 includingcopper deposited on a titanium (Ti) film, a copper bump 162 and abackside metal film 163. As the backside metal film 163, a depositionfilm (Au/Ni film) including gold (Au) deposited on nickel (Ni) andhaving a film thickness of about 2 to 4 μm may be exemplified. Thecopper bump 162 is formed to fill the inside of the opening 151 via theseed film 161 by the electrolytic plating method and also serves as thethrough-plug V.

The bump is formed so that a height (bump height) protruding from thebackside of the semiconductor substrate 50 is about 8 μm or smaller. Thebump is preferably formed so that the exposed surface side (the lowersurface in FIG. 1) of the backside bump 160 is smooth. After forming thebackside bump 160, the support substrate is removed.

By the above processes, the semiconductor chip including the TSVs 200including the structure shown in FIG. 1 is completely formed, so thatthe semiconductor device of this exemplary embodiment is completed.

In addition to the above specific example, the invention can be alsoused as a method for forming an opening including a tapered portion in asemiconductor substrate when forming a device including a MEMS (MicroElectro Mechanical Systems) structure, such as acceleration sensor.Also, the material for filling the inside of the formed opening is notlimited to the insulation film. For example, even when the opening isfilled with a conductive film by the CVD, the invention can be applied.

In addition, the substrate in which the opening is to be formed is notlimited to the substrate of a silicon single layer. For example,regarding a SOI (Silicon On Insulator) substrate in which asemiconductor layer having a thickness of about 10 to 100 μm is formedon an insulation film, the invention can be used as a method forprocessing the semiconductor layer.

The opening width and opening depth for the insulation ring that isformed by the invention are not limited with respect of the sizesthereof. However, when the invention is applied for forming an openinghaving an aspect ratio of 10 or greater, it is possible to realize thegreat effect from a standpoint of improvement on the embeddingcharacteristic.

In the below, modified embodiments of the first exemplary embodimentwill be described.

First Modified Embodiment

This modified embodiment is different from the first exemplaryembodiment, in that after the trench for insulation ring 150 c isformed, an etching process for smoothing the protrusions by thescalloping is further performed. In the below, only the processdifferent from the first exemplary embodiment will be described and thedescriptions of the other processes will be omitted.

FIG. 23A is a sectional view after the process of FIG. 8 of the firstexemplary embodiment is completed. As shown in FIG. 23A, after thetrench for insulation ring 150 c is formed, protrusions 5 by thescalloping are formed on the inner wall side surface of the trench forinsulation ring 150 c. As shown in FIG. 23B, the protrusions 5 areremoved by etching the inner wall of the trench for insulation ring 150c.

In this modified embodiment, it is possible to further smooth thetapered portion and the vertical portion, compared to the firstexemplary embodiment. As a result, it is possible to prevent the voidfrom being formed in the insulation ring more effectively, compared tothe first exemplary embodiment, thereby effectively suppressing themanufacturing yield from being lowered.

Second Modified Embodiment

This modified embodiment is different from the first exemplaryembodiment, in that after the trench for insulation ring 150 c isformed, a process for forming an insulation film on the inner wall sidesurface of the trench for insulation ring 150 c and an etching processfor etching the inner wall side surface of the trench for insulationring 150 c are further performed. In the below, only the processdifferent from the first exemplary embodiment will be described and thedescriptions of the other processes will be omitted.

As shown in FIG. 24A, after the process of FIG. 8 of the first exemplaryembodiment is completed, an insulation film is formed on a whole surfaceand an etch-back process is performed. Thereby, an insulation film 6 isformed on the inner wall side surface of the trench for insulation ring150 c in such a degree that a part of the protrusions 5 by thescalloping is exposed. As shown in FIG. 24B, the inner wall side surfaceof the trench for insulation ring 150 c are etched. At this time, theprotrusions 5 are preferentially removed due to a difference betweenetching rates of the insulation film 6 and the semiconductor substrate50. By the etching conditions, the insulation film 6 may be removed orremained. However, it is preferable to remove the insulation film 6 soas to enlarge a diameter of the trench for insulation ring 150 c aslarge as possible.

As the insulation film, TEOS-NSG (Tetraethyl orthosilicateTetraethoxysilane-None-doped Silicate Glass) may be used. The etchingconditions may include conditions that the gas including SF₆ and NH₃ isused and the high temperature such as 100° C. or higher is set.

In addition, after etching the insulation film, an insulation film maybe further formed on the inner wall side surface of the trench forinsulation ring 150 c for smoothing. Furthermore, considering the seriesof processes of forming the insulation film on the inner wall sidesurface of the trench for insulation ring 150 c, etching the inner wallside surface of the trench for insulation ring 150 c and forming theinsulation film on the inner wall side surface of the trench forinsulation ring 150 c as one cycle, a plurality of the cycles may beperformed.

In this modified embodiment, it is possible to further smooth thetapered portion and the vertical portion, compared to the firstexemplary embodiment. As a result, it is possible to prevent the voidfrom being formed in the insulation ring more effectively, compared tothe first exemplary embodiment, thereby effectively suppressing themanufacturing yield from being lowered.

Second Exemplary Embodiment

Next, an application example of the first exemplary embodiment will bedescribed.

FIG. 18 is a sectional view of a highly integrated package with thestacked two DRAM chips including TSVs, which are formed according to thefirst exemplary embodiment. Semiconductor chips 323, 324 are core chipsof the DRAMs that are formed according to this exemplary embodiment, andincludes as a memory cell circuit and a peripheral circuit for datainput and output with respect to the memory cell. The specific structureof the TSV is the same as the above structure and thus is not shown inFIG. 18.

The semiconductor chips 323, 324 comprise the TSVs including the samestructure. In the below, the semiconductor chip 323 will be described asan example. The semiconductor chip 323 comprises a plurality of TSVs 323c, each of which comprises a backside bump 323 a, and a topside bump 323b connected with each other.

The semiconductor chip 322 functions as an interface chip and is madefrom a logic circuit that controls input and output of data with regardto each of the DRAM core chips 323, 324 and input and output of data tothe outside of the package. The interface chip 322 also includes TSVs,which are formed by the above exemplary embodiment, and the same topsideand backside bumps as the DRAM core chips 323, 324.

Each of the semiconductor chips is individualized by dicing afterforming the TSVs. The semiconductor chips to be stacked have the samearrangement of the TSVs and may have different chip sizes.

The uppermost semiconductor chip 324 comprises a surface that includesthe topside bump and is fixed to a metal lead frame 326 by an attachingfilm 325. By repeating processes of arraigning the TSVs of the threesemiconductor chips with each other and temporarily fixing the TSVs witheach other by low-temperature (about 150 to 170° C.) heating, the threesemiconductor chips are sequentially stacked. At this time, by primarilyfixing the uppermost semiconductor chip 324 and the lead frame 326, itcan be used as a basis when stacking the respective chips. After all thesemiconductor chips are stacked, the respective semiconductor chips arecompletely fixed by applying the temperature of about 250 to 300° C.under the constant pressure.

A reference numeral 321 indicates a base substrate. The base substrate321 and the lowermost semiconductor chip 322 are connected via terminals329. A resin 330 is filled between the semiconductor chips, therebyprotecting the respective semiconductor chips. The base substrate 321has a plurality of soldered balls 327 and is connected to the TSVs ofthe interface chip 322 via a wiring layer 328 and the terminals 329. Thesoldered balls 327 are applied with input and output signals from theoutside, a power supply voltage and the like. In the meantime, three ormore semiconductor chips may be stacked.

FIG. 19 is a pictorial view showing a memory module including DRAMpackages manufactured as described above. A reference numeral 402indicates a DRAM package that is manufactured as shown in FIG. 18 and ismounted on a printed substrate 400. The printed substrate 400 comprisesa plurality of input/output terminals (I/O terminals) 401 forelectrically connecting the memory module to an external device. Thedata is input and output to and from the respective DRAM packages 402via the I/O terminals 401.

The memory module comprises a control chip 403 that controls theinput/output of the data to and from the respective DRAM packages. Thecontrol chip 403 performs timing adjustment of a clock signal that isinput from the outside of the memory module, shaping of a signalwaveform and the like, thereby supplying the same to the respective DRAMpackages. In the meantime, only the plurality of DRAM packages may bemounted without arranging the control chip 403 on the printed substrate400.

By using this exemplary embodiment, it is possible to easily manufacturea DRAM chip with high integration corresponding to the miniaturization,thereby making it possible to form a memory module corresponding to datastorage of large capacity. By using the above memory module includingthe DRAM chips formed by this exemplary embodiment, it is possible toform a data processing device that will be described in the below.

Third Exemplary Embodiment

FIG. 20 schematically shows a configuration of a data processing device500 according to this exemplary embodiment. The data processing device500 includes a calculation processing device (processor) 520 and a DRAMmemory module 530, which are connected to each other via a system bus510. The processor 520 may be a micro processing unit (MPU), a digitalsignal processor (DSP) and the like. The DRAM memory module 530comprises a DRAM chip that is formed according to this exemplaryembodiment. In addition, a read only memory (ROM) 540 for storing fixeddata may be connected to the system bus 510.

Although only one system bus 1 is shown for simplification, a pluralityof system buses may be connected serially or in parallel through aconnector and the like, as required. In addition, the respective devicesmay be connected to each other by a local bus, rather than the systembus 510.

Also, in the data processing device 500, a non-volatile storage device550 and an input/output device 560 are connected to the system bus 510,as required. As the non-volatile bus, a hard disk drive, an opticaldrive, a solid state drive (SSD) and the like may be used as thenon-volatile storage device. The input/output device 560 includes adisplay device such as liquid crystal display and a data input devicesuch as keyboard, for example.

In FIG. 21, the number of each constitutional element of the dataprocessing device 500 is one for simplification. However, the inventionis not limited thereto and one or more of each constitutional elementmay be provided in plural. The data processing device 500 includes acomputer system, for example. However, the invention is not limitedthereto.

By using this exemplary embodiment, it is possible to easily manufacturea DRAM chip with high integration corresponding to the miniaturization,thereby making it possible to form a data processing device having highperformance.

It is apparent that the present invention is not limited to the aboveembodiments, but may be modified and changed without departing from thescope and spirit of the invention.

In addition, while not specifically claimed in the claim section, theapplications reserve the right to include in the claim section at anyappropriate time the following semiconductor device and method:

-   1. A method of manufacturing a semiconductor device, comprising:

forming a first opening in a semiconductor substrate, the first openingincluding inner wall side surface with a tapered shape and including asectional area that is gradually decreased from a first surface of thesemiconductor substrate toward a thickness direction thereof; and

forming a second opening including a sectional area that is constantfrom a bottom surface of the first opening toward the thicknessdirection of the semiconductor substrate.

-   2. The method according to the above 1,

wherein in forming the first opening, a cycle containing the followingsteps (1)-(3) is repeated a plurality of times, and a sectional area ofa third opening formed by step (1) is decreased every one cycle.

(1) etching the semiconductor substrate to form a third opening;

(2) forming a protective film on an inner wall of the third opening; and

(3) removing the protective film formed on a bottom surface of the innerwall of the third opening.

-   3. The method according to the above 2,

wherein an etching time of the step(1) is shortened every one cycle.

-   4. The method according to the above 1,

wherein in forming the second opening, a cycle containing the followingsteps (A)-(C) is repeated a plurality of times, and a sectional area ofa fourth opening formed by step (A) of each cycle is the same.

(A) etching the semiconductor substrate to form a fourth opening;

(B) forming a protective film on an inner wall of the fourth opening;and

(C) removing the protective film formed on a bottom surface of the innerwall of the fourth opening.

-   5. The method according to the above 1, further comprising etching    inner wall side surfaces of the first and second openings to smooth    the inner wall side surfaces of the first and second openings, after    forming the second opening.-   6. The method according to the above 1, after forming the second    opening, further comprising:

forming an insulation film on the inner wall side surfaces of the firstand second openings; and,

etching the inner wall side surfaces of the first and second openingsincluding the insulation film formed thereon to smooth the inner wallside surfaces of the first and second openings.

-   7. A semiconductor device, comprising:

a first film;

one or more openings for a tapered portion formed from a surface of thefirst film toward an inside of the first film; and

two or more openings for a vertical portion formed below the opening forthe tapered portion in the first film,

wherein the opening for the tapered portion has a sectional area S_((n))(n: an integer of 1 or greater) of a section perpendicular to athickness direction of the first film, the S_((n)) being changed in thethickness direction and having a maximum value S_((n)max) (n: an integerof 1 or greater) of the S_((n)),

wherein the openings for the vertical portion have a sectional areaS′_((a)) (a: an integer of 1 or greater) of a section perpendicular tothe thickness direction of the first film, the S′_((a)) being changed inthe thickness direction, and a maximum value S′_((a)max) (a: an integerof 1 or greater) of the S′_((a)) of each opening for the verticalportion is a constant value, and

wherein S′_((a)max) is smaller than any S_((n)max).

-   8. The semiconductor device according to the above 7,

wherein the semiconductor device comprises two or more openings for thetapered portion,

the S_((n)max) of each opening for the tapered portion is graduallydecreased from the surface of the first film toward the thicknessdirection thereof, and

the S_((n)max) of the lowermost opening for the tapered portion farthestfrom the surface of the first film in the thickness direction thereof,is greater than the S′_((a)max).

-   9. The semiconductor device according to the above 7,

wherein the first film includes an electrode formed so as to penetratethrough the first film in a thickness direction,

the opening for the tapered portion and the openings for the verticalportion communicating with each other penetrate through the first filmin the thickness direction thereof,

an insulation film is embedded in the opening for the tapered portionand the openings for the vertical portion,

the insulation film embedded in the opening for the tapered portion andthe openings for the vertical portion is an insulation ring, and

the insulation ring is formed so as to penetrate through the first filmand so as to surround an outer side surface of the electrode.

-   10. A data processing device including a plurality of the    semiconductor devices according to the above 9,

wherein each semiconductor device is connected to each other via theelectrodes,

the data processing device further comprises a calculation processingdevice, and

the calculation processing device is connected to each semiconductordevice via a system bus.

-   11. The data processing device according to the above 10, wherein    each semiconductor device is a semiconductor chip that can perform a    storage operation as a DRAM.

The invention claimed is:
 1. A semiconductor device, comprising: asemiconductor substrate with a first main surface and an opposite,second main surface; and a hole penetrating the semiconductor substratethrough the first and second main surfaces, the hole including a taperedportion contacting with the first main surface and a vertical portioncontacting with the tapered portion and the second main surface, thetapered portion comprising at least first and second scallop openings inthat order from the first main surface toward the vertical portion, eachof the first and second scallop openings including a first end close tothe first main surface and a second end close to the second mainsurface, the first and second scallop openings respectively includingfirst and second convex side surface, the convex side surface beingdefined such that a diameter of the hole at the second end of each ofthe first and second scallop openings is smaller than a diameter of thehole at an intermediate point between the first and second ends of therespective first and second scallop openings, the second end of thefirst scallop opening contacting with the first end of the secondscallop opening, and a first diameter of the hole at the second end ofthe first scallop opening being larger than a second diameter of thehole at the second end of the second scallop opening, the verticalportion comprising a plurality of scallop openings arranged in series,the plurality of scallop openings each including a convex side surface.2. The semiconductor device as claimed in claim 1, the semiconductordevice further comprising: an insulating film covering a surface exposedby the hole of the semiconductor substrate; and a conductive viaprovided in the hole through the insulating film, wherein a plurality ofthird diameters of the hole at respective connecting points of twoscallop openings adjacently arranged among the plurality of scallopopenings are substantially the same as one another and smaller than thesecond diameter.
 3. The semiconductor device as claimed in claim 1,wherein the first scallop opening has a first depth in a directionperpendicular to a surface of the semiconductor substrate, and thesecond scallop opening has a second depth smaller than the first depthin the direction.
 4. The semiconductor device as claimed in claim 3,wherein the plurality of scallop openings each has a third depth smallerthan the second depth in the direction.
 5. The semiconductor device asclaimed in claim 1, wherein the first end of the first scallop openingcontacts with the first main surface.
 6. The semiconductor device asclaimed in claim 1, wherein the first and second scallop openings have asmoothed shape at a region where the second end of the first scallopopening contacts with the first end of the second scallop opening. 7.The semiconductor device as claimed in claim 1, the semiconductor devicefurther comprising: a transistor provided on the first surface of thesemiconductor substrate; and an interlayer insulating film formed on thefirst substrate and covering the transistor, the interlayer insulatingfilm including a second hole penetrating therethrough and aligned withthe hole provided in the semiconductor substrate, wherein the conducivevia is provided in the second hole.
 8. The semiconductor device asclaimed in claim 7, the semiconductor device further comprising: a seedlayer provided between the conductive via and the interlayer insulatingfilm in the second hole and between the conductive via and theinsulating film in the hole provided in the semiconductor substrate. 9.The semiconductor device as claimed in claim 7, the semiconductor devicefurther comprising: a bump provided over the second surface of thesemiconductor substrate, the bump and the conductive via being molded asone piece.
 10. The semiconductor device as claimed in claim 7, thesemiconductor device further comprising: a second interlayer insulatingfilm formed over the interlayer insulating film; a plurality of contactplugs penetrating the second interlayer insulating film and electricallyconnected to the conductive via; and a conductive bump provided over thesecond interlayer insulating film and electrically connected to theplurality of contact plugs.
 11. A semiconductor device, comprising: aplurality of memory chips each including a memory cell and a peripheralcircuit to communicate a data with the memory cell; each of the memorychips comprising: a semiconductor substrate including a first mainsurface and a second main surface opposing the first main surface; and ahole penetrating in the semiconductor substrate through the first andsecond main surfaces, and including a tapered portion contacting withthe first main surface and a vertical portion contacting with thetapered portion and the second main surface, an insulating film coveringa surface of the semiconductor substrate exposed by the hole; and aconductive via provided in the hole through the insulating film, thetapered portion comprising at least first and second scallop openings inthat order from the first main surface toward the vertical portion, eachof the first and second scallop openings including a first end close tothe first main surface and a second end close to the second mainsurface, the first and second scallop openings respectively includingfirst and second convex side surface, the convex side surface beingdefined such that a diameter of the hole at the second end of each ofthe first and second scallop openings is smaller than a diameter of thehole at an intermediate point between the first and second ends of therespective first and second scallop openings, the first end of the firstscallop opening contacting with the first main surface, the second endof the first scallop opening contacting with the first end of the secondscallop opening, a first diameter of the hole at the second end of thefirst scallop opening being larger than a second diameter of the hole atthe second end of the second scallop opening, the vertical portioncomprising a plurality of scallop openings arranged in series, theplurality of scallop openings each including a convex side surface,wherein the plurality of memory chips are connected to one anotherthrough the respective conductive via.
 12. The semiconductor device asclaimed in claim 11, wherein, a plurality of third diameters of the holeat respective connecting points of two scallop openings adjacentlyarranged among the plurality of scallop openings being substantially thesame as one another and smaller than the second diameter, and the firstscallop opening has a first depth in a direction perpendicular to asurface of the semiconductor substrate, and the second scallop openinghas a second depth smaller than the first depth in the direction. 13.The semiconductor device as claimed in claim 12, wherein the pluralityof scallop openings each has a third depth smaller than the second depthin the direction.
 14. The semiconductor device as claimed in claim 13,wherein the first and second scallop openings have a smoothed shape at aregion where the second end of the first scallop opening contacts withthe first end of the second scallop opening.
 15. The semiconductordevice as claimed in claim 11, the semiconductor device furthercomprising: a transistor provided on the first surface of thesemiconductor substrate.
 16. The semiconductor device as claimed inclaim 13, wherein the tapered portion further comprises a third scallopopening so that the first, second and third scallop openings arearranged in that order from the first main surface toward the verticalportion, the third scallop opening including a first end close to thefirst main surface and a second end close to the second main surface,wherein the third scallop opening includes a third convex side surface,wherein the second end of the second scallop opening contacts with thefirst end of the third scallop opening, and wherein a fourth diameter ofthe hole at the second end of the third scallop openings is smaller thanthe second diameter and larger than the third diameter.
 17. Thesemiconductor device as claimed in claim 16, wherein the third scallopopening has a fourth depth smaller than the second depth and larger thanthe third depth in the direction.